A scanning probe microscopy (hereinafter, referred to as an ‘SPM’) is a general term for microscopes that observe the three-dimensional shape of a sample surface as physical information of the sample surface with high magnification of nanometer size by scanning the sample surface using a fine probe (cantilever) as a probe. SPMs may be classified into various types of SPMs according to which kind of physical quantity of a sample the probe detects, as shown in FIG. 10.
In addition, the SPMs are very advantageous particularly in the evaluation of a semiconductor device, the evaluation of the quantum structure, and the observation of a biomolecule and are mentioned as observation apparatuses which will develop hereafter. That is, for the semiconductor device, high vertical resolution of the SPM is expected since observation of irregularities of a thin film is required as a thin film technique is developed. In addition, the SPM is used since the electrical property of a semiconductor material in which impurities (dopant atoms) are mixed can be measured with high precision and a distribution situation of the dopant atoms in the semiconductor material can be evaluated.
Furthermore, in evaluation of the quantum structure, the SPM is used as almost a sole observation means for evaluating the quantum structure of each shape of for example, a quantum dot or quantum wire having a size of about 10 nm with high spatial resolution regarding electrical and optical properties. Moreover, in observation of a biomolecule, the SPM can obtain high spatial resolution and does not damage the biomolecule because electron irradiation or observation under vacuum is not performed and accordingly, the biomolecule can be observed in a live state. For the observation of biomolecules, an atomic force microscope (hereinafter, referred to as an ‘AFM’) and a near-field scanning optical microscope (hereinafter, referred to as an ‘NSOM’) are especially used, and a range of utilization of these microscopes is expected to extend.
Regarding the observation of biomolecules, by the use of the AFM or NSOM, it became possible to observe how protein moves in an antigen-antibody reaction to change the bond or to observe generation of a force or movement of myosin concerned with muscular contraction and a process of transport of an ATP (adenosine triphosphate) molecule, which is fluorescently labeled, by using protein in a live state. On the other hand, in the case of the AFM, not only two-dimensional imaging indicating the height and hardness of a sample can be performed by contact, dynamic, and phase modes, but also controls of force modulation, a magnetic force (MFM), a current, a surface potential (KFM), nanoindentation for making a hole in a sample in a nanometer size, the atmosphere can be comparatively easily performed. In addition, since there is no limitation in a sample, a biological sample can also be measured.
However, even in the case of SPMs, a large apparatus needs to be remodeled in order to change the environment around a sample, especially an optical environment. This was a big problem in terms of both cost and remodeling time. For this reason, there was almost no technique allowing light to be irradiated onto a sample in the SPM. On the other hand, since irradiation of light onto a sample has been generally performed in an optical microscope until now, a function of light irradiation for dissociating a caged compound is typically mounted as an additional function of a microscope commercially available.
Here, the caged compound refers to a compound which confines a material, which gives the activity, with another molecule, which reacts to light (light having a specific wavelength), as a method of controlling the activity in a biomolecule, for example. Specifically, the caged compound indicates a compound obtained by bonding a photodissociable protecting group, such as a nitrobenzene group, to a bioactive material in order to control the activity of the bioactive material. That is, the bioactive material is in a physiologically inactive state when the bioactive material is bonded to the photodissociable protecting group. However, the state of the bioactive material can be changed to an active state by dissociating the bonding between the bioactive material and the photodissociable protecting group by irradiation of ultraviolet rays and the like, and drug stimulation can be given to a biomolecule by the bioactive material.
That is, the composition of molecules included in a solution can be changed by irradiating light onto the caged compound. Accordingly, for example, an operation of giving drug stimulation can be performed on a cell at a required timing. Since a laser beam is irradiated as the light described above, it is necessary to dispose optical components, such as an optical path, a condensing lens, and an iris with high precision.
Furthermore, since a device of the SPM is expensive, many researchers share one SPM in many cases. For this reason, the device should be simply installed and detached, but there have been no such optical devices. A method of directly irradiating light from the outside, for example, with a laser using an optical fiber may also be considered. Also in this case, an adjustment of an optical axis of a laser beam is complicated and the system size becomes large. Accordingly, it is not possible to easily detach the device from the SPM.
Regarding irradiation of light onto the sample described above, a high-speed atomic force microscope has been newly developed, being provided as an SPM capable of performing irradiation of light onto a sample (for example, refer to JP-A-2005-106790). The technique of irradiation of light onto a sample disclosed in JP-A-2005-106790 is applied to a case where an optical microscope is combined to the SPM. Accordingly, the technique is based on a light irradiation technique using an optical microscope in the related art, and reaction caused by the light irradiation is restricted to a case of using a caged compound.
In the SPM disclosed in JP-A-2005-106790, a scanning mechanism that relatively scans a cantilever existing in a solution and a substrate, on which a sample is mounted, in a state where the sample is dipped in the solution and an irradiation mechanism that irradiates release light to a photodissociable protecting group of a caged compound existing in the solution or in the sample are provided. However, the irradiation mechanism in the SPM is formed integrally with the device of the SPM and has a large-scale, expensive, and complicated system configuration. Since the irradiation mechanism is united with the device of the SPM, the irradiation mechanism cannot be shared for other SPMs, which is a disadvantage. Furthermore, in the case of the SPM described above, since a cantilever exists between a light source and a sample when irradiating light onto a solution near the sample, the light is blocked by the cantilever. As a result, irradiation of light cannot be effectively performed on the sample or the solution, onto which the light needs to be irradiated most, located below the cantilever.